JP2016058584A - Patterning method, photomask, and template for nanoimprint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a patterning method capable of reducing the number of steps, by preventing formation of a fingerprint pattern, and to provide a photomask and a template for nanoimprint produced by using the patterning method.SOLUTION: A patterning method forms a first region and a second region on a processed layer. The first region has a guide pattern. In the second region, affinity for any one of a first segment or second segment contained in a self-organization material is higher than that for the other. The self-organization material is applied on the first region and second region. Phase separation of the self-organization material to a first domain having the first segment and a second domain having the second segment is carried out. Any one of the first domain or second domain is removed selectively.SELECTED DRAWING: Figure 6

Description

  Embodiments described herein relate generally to a pattern formation method, a photomask, and a nanoimprint template.

  In recent years, the use of Directed Self-Assembly (DSA) has attracted attention as a fine patterning technology. In general, in a pattern formation method using DSA, patterning is performed on the entire surface of a layer to be processed in a lump. For this reason, when the area | region which forms a pattern on the surface of a to-be-processed layer and the area | region which does not form a pattern are mixed like a semiconductor device, patterning is performed also to the area | region which does not form a pattern.

JP 2013-97863 A (U.S. Pat. No. 8,501,022) JP 2008-036491 A

  A pattern forming method capable of preventing the formation of a fingerprint pattern and reducing the number of steps, and a photomask and a nanoimprint template manufactured using the pattern forming method are provided.

  The pattern formation method which concerns on one Embodiment forms a 1st area | region and a 2nd area | region on a to-be-processed layer. The first region has a guide pattern. In the second region, the affinity for one of the first segment and the second segment contained in the self-assembled material is higher than the affinity for the other. A self-assembling material is applied over the first region and the second region. The self-assembled material is phase separated into a first domain having a first segment and a second domain having a second segment. Either one of the first domain and the second domain is selectively removed.

The top view and sectional drawing explaining the pattern formation method which concerns on 1st Embodiment. The top view and sectional drawing explaining the pattern formation method which concerns on 1st Embodiment. The top view and sectional drawing explaining the pattern formation method which concerns on 1st Embodiment. The top view and sectional drawing explaining the pattern formation method which concerns on 1st Embodiment. The top view and sectional drawing explaining the pattern formation method which concerns on 1st Embodiment. The top view and sectional drawing explaining the pattern formation method which concerns on 1st Embodiment. The top view and sectional drawing explaining the pattern formation method which concerns on 1st Embodiment. The top view and sectional drawing explaining the pattern formation method which concerns on 1st Embodiment. The figure which shows an example of a fingerprint pattern. The top view and sectional drawing explaining the pattern formation method which concerns on 2nd Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
A pattern forming method according to the first embodiment will be described with reference to FIGS. In this pattern forming method, a fine pattern is formed on a processing object using a self-organizing material. The self-assembled material is, for example, a block copolymer such as a diblock copolymer or a triblock copolymer, but is not limited thereto. A block copolymer is a copolymer in which a plurality of types of polymers are chemically bonded. Below, each polymer which comprises a block copolymer is called a segment.

  The block copolymer has a hydrophilic first segment and a hydrophobic second segment. The hydrophilicity and hydrophobicity here are relative properties. That is, the first segment is a segment having the highest hydrophilicity among the segments constituting the block copolymer, and the second segment is the most hydrophobic among the segments constituting the block copolymer (hydrophilic Segment). Therefore, the first segment is more hydrophilic than the second segment, and the second segment is more hydrophobic (lower hydrophilic) than the first segment.

  In the present embodiment, the block copolymer is, for example, PS-b-PMMA or PS-b-PDMS, but is not limited thereto. When the block copolymer is PS-b-PMMA, the first segment is PMMA (polymethyl methacrylate) and the second segment is PS (polystyrene).

  Here, FIGS. 1-8 has shown the process target in each process of this pattern formation method. 1 to 8, (a) is a plan view, and (b) is a cross-sectional view taken along the line AA ′ of (a).

  First, as shown in FIGS. 1A and 1B, the base layer 2 is formed on the layer 1 to be processed, and the neutralization film 3 is formed on the base layer 2.

  The layer 1 to be processed is a processing target for forming a line and space pattern using this pattern forming method. In FIG. 1, the layer 1 to be processed is a quartz glass substrate, but is not limited thereto. The layer 1 to be processed may be, for example, a semiconductor substrate or a glass substrate. Moreover, the layer 1 to be processed may be an arbitrary layer formed on the substrate.

  The layer 1 to be processed has a pattern region (first region) 11 and a non-pattern region (second region) 12. The pattern region 11 is a region where a line and space pattern is formed on the layer 1 to be processed in a later step. Moreover, the non-pattern area | region 12 is an area | region where a line and space pattern is not formed in the to-be-processed layer 1 in a post process.

  The underlayer 2 is a hard mask for transferring the microphase separation pattern (line and space pattern) of the block copolymer formed in the subsequent process to the layer 1 to be processed. The underlayer 2 is formed on both the pattern region 11 and the non-pattern region 12 on the layer 1 to be processed.

  The underlayer 2 is formed of any material having an etching selectivity with respect to the layer 1 to be processed and having an affinity for either the first segment or the second segment of the block copolymer. Affinity here is a relative property. That is, that the foundation layer 2 has an affinity for the first segment means that the affinity of the foundation layer 2 for the first segment is higher than the affinity for the second segment. Similarly, that the underlayer 2 has an affinity for the second segment means that the affinity of the underlayer 2 for the second segment is higher than the affinity for the first segment.

  In FIG. 1, the underlayer 2 includes a metal such as Cr, but is not limited thereto. The metal contained in the underlayer 2 may be, for example, Si, Mo, Ta. The underlayer 2 is formed by laminating such a material on the layer 1 to be processed by a sputtering method or the like.

  The neutralized film 3 constitutes a guide pattern when the block copolymer is microphase-separated in a subsequent process. The neutralization film 3 is formed on both the pattern region 11 and the non-pattern region 12 on the base layer 2.

  The neutralized film 3 is a thin film that is neutral with respect to the first segment and the second segment of the block copolymer. Neutral here means having the same degree of affinity for the first segment and the second segment. The neutralized film 3 can be formed by, for example, a mixture of the first segment alone and the second segment alone, or a random copolymer of the first segment and the second segment.

  Specifically, when the block copolymer is PS-b-PMMA, a mixture of PS and PMMA or PS-r-PMMA, which is a random copolymer of PS and PMMA, is converted into PGMEA (polyethylene glycol monomethyl ether acetate). What was dissolved at a concentration of 1.0 wt% was spin-coated at a rotational speed of 2000 rpm, baked on a hot plate at 110 ° C. for 90 seconds, and then baked at 240 ° C. for 3 minutes, whereby the neutralized film 3 was formed. Can be formed.

Next, as shown in FIGS. 2A and 2B, a resist pattern 4 having a line and space pattern is formed on the neutralization film 3. The resist pattern 4 is formed by spin-coating a resist material on the entire surface of the neutralization film 3 and removing a part of the resist material by exposure and development. The thickness of the resist material to be applied is, for example, 100 nm. In addition, the exposure is performed, for example, with an ArF excimer laser at an exposure amount of 20 mJ / cm ² .

  More specifically, the resist material applied to the pattern region 11 on the neutralization film 3 has the space portion of the above-described line and space pattern shape removed. Thereby, the resist pattern 4 is formed in the pattern region 11. The neutralization film 3 is exposed from the space portion of the pattern region 11.

  On the other hand, all the resist material applied to the non-pattern region 12 on the neutralization film 3 is removed. As a result, the resist pattern 4 is not formed in the non-pattern region 12. In the non-pattern region 12, the neutralization film 3 is exposed on the entire surface.

  Next, as shown in FIGS. 3A and 3B, the neutralization film 3 is etched using the resist pattern 4 as a mask. The neutralization film 3 is processed by, for example, dry etching using oxygen. Then, after the neutralization film 3 is etched, the resist pattern 4 is removed. The resist pattern 4 can be peeled off by using, for example, thinner.

  As a result, the resist pattern 4 is transferred to the pattern region 11 to form a guide pattern having a line and space pattern. The guide pattern is composed of the base layer 2 (space portion) exposed from the portion where the neutralization film 3 is removed and the neutralization film 3 (line portion) remaining without being removed. This guide pattern serves as a guide for regularly arranging the first segment and the second segment during microphase separation of the block copolymer in the subsequent step. In this guide, the underlayer 2 functions as a chemical guide, and the neutralization film 3 functions as a physical guide.

  Further, the neutralization film 3 of the non-pattern region 12 is all removed by this etching. Thereby, in the non-pattern area | region 12, the base layer 2 is exposed to the whole surface. Therefore, the non-pattern region 12 is a region having affinity for either one of the first segment and the second segment.

  Next, as shown in FIGS. 4A and 4B, a block copolymer having a first segment and a second segment is spin-coated on the base layer 2 and the neutralized film 3, so that the block copolymer layer is formed. 5 is formed. When the block copolymer is PS-b-PMMA, PS-b-PMMA is dissolved in PGMEA so as to have a concentration of about 1.0 wt%, and is spin-coated at a rotational speed of 2000 rpm. The film thickness of the block copolymer layer 5 from the underlayer 2 is, for example, 35 nm.

  Next, as shown in FIGS. 5A and 5B, the block copolymer layer 5 is annealed. Thereby, the block copolymer layer 5 microphase-separates into the 1st domain 51 which has a 1st segment, and the 2nd domain 52 which has a 2nd segment, and a microphase-separation pattern is formed.

  By this annealing process, a lamellar structure microphase separation pattern 13 in which the first domains 51 and the second domains 52 are alternately arranged in the plane direction is formed in the pattern region 11. This is because, in the pattern region 11, a guide pattern having the base layer 2 and the neutralization film 3 is formed, and the block copolymer is microphase-separated according to the guide pattern.

  For example, when the underlayer 2 has an affinity for the first segment, the first segment is pinned to a portion where the underlayer 2 is exposed, that is, a space portion of the guide pattern, to form the first domain 51. Then, on the neutralization film 3, that is, in the line portion of the guide pattern, the first segment and the second segment are alternately arranged starting from the first domain 51 formed in the space portion.

  Thereby, as shown in FIG. 5, a lamellar structure in which the first domains 51 and the second domains 52 are alternately arranged in the plane direction is formed. The same applies to the case where the underlayer 2 has affinity for the second segment, and the pattern region 11 has a lamellar structure microphase separation pattern in which the positions of the first domain 51 and the second domain 52 are interchanged with those in FIG. It is formed.

  Since the microphase separation pattern 13 is formed along the guide pattern, it has a line and space pattern shape parallel to the guide pattern. Further, as described above, since the microphase separation pattern 13 has a plurality of patterns formed on the neutralization film 3 of the guide pattern, the microphase separation pattern 13 has a finer line and space pattern than the guide pattern. In the subsequent process, the microphase separation pattern 13 is transferred to the layer 1 to be processed.

  In addition, the dimension of the space part and line part of a guide pattern can be made into the arbitrary dimension which can guide the micro phase separation of the block copolymer layer 5. FIG.

  On the other hand, a lamellar structure microphase separation pattern 14 in which the first domains 51 and the second domains 52 are alternately arranged in the height direction is formed in the non-pattern region 12. This is because the base layer 2 is exposed on the entire surface in the non-pattern region 12.

  For example, when the underlayer 1 has affinity for the first segment, the first segment is pinned to a portion where the underlayer 2 is exposed as described above. Since the underlayer 2 is exposed on the entire surface of the non-pattern region 12, the first segment is pinned on the underlayer 2 over the entire surface of the non-pattern region 12. As a result, a layer of the first domain 51 parallel to the underlayer 2 is formed on the underlayer 2. Then, with the first domain 51 as a starting point, the first segment and the second segment are arranged.

  Thereby, as shown in FIG. 5B, a lamellar structure microphase separation pattern 14 in which the layers of the first domains 51 and the layers of the second domains 52 are alternately stacked in the height direction is formed. The same applies to the case where the underlayer 2 has an affinity for the second segment. The pattern region 12 has a lamellar structure microphase separation pattern in which the positions of the first domain 51 and the second domain 52 are interchanged with those in FIG. It is formed.

  For example, when the block copolymer is PS-b-PMMA, annealing is performed at 220 ° C. for 3 minutes in a nitrogen atmosphere. Thereby, PS-b-PMMA undergoes microphase separation, and the above-described microphase separation patterns 13 and 14 are formed. That is, in the pattern region 11, a microphase separation pattern 13 having a line and space pattern shape having a PMMA domain (first domain 51) and a PS domain (second domain 52) having a half pitch of about 15 nm is formed. In the non-pattern region 12, a PMMA domain layer having a thickness of about 5 nm is formed on the underlayer 2, and a PS domain layer and a PMMA domain layer having a thickness of about 15 nm are formed thereon. .

  The number of layers of the first domain 51 and the second domain 52 formed in the non-pattern region 12 is arbitrary, and the film thickness of the block copolymer layer 5, the first segment 51 and the second segment of the block copolymer It changes according to the length of the segment 51.

  Next, as shown in FIGS. 6A and 6B, the first domain 51 is selectively removed by etching. As a result, a line-and-space pattern (microphase separation pattern 13 ′) having the second domain 52 as a line portion is formed in the pattern region 11. Further, the layer of the second domain 52 is exposed in the non-pattern region 12.

  For example, when the block copolymer is PS-b-PMMA, PMMA (first domain 51) can be selectively removed by dry etching using nitrogen.

  Note that the second domain 52 may be selectively removed instead of the first domain 51. In this case, a line and space pattern having the first domain 51 as a line portion is formed in the pattern region 11. In addition, the layer of the first domain 51 is exposed in the non-pattern region 12.

  Next, as shown in FIGS. 7A and 7B, the underlying layer 2 is etched using the second domain 52 as a mask. As a result, the microphase separation pattern 13 is transferred to the pattern region 11 of the base layer 2 to form a line and space pattern. The non-pattern region 12 of the underlayer 2 is not etched because the entire surface is masked by the second domain 52.

  For example, when the block copolymer is PS-b-PMMA, the underlayer 2 can be removed by dry etching using a chlorine-based gas. As a result, a line and space pattern having a half pitch of about 15 nm is formed in the pattern region 11 of the underlayer 2.

  In the previous step, when the second domain 52 is selectively removed, the underlying layer 2 may be etched using the first domain 51 as a mask. As a result, a line and space pattern in which the line portion and the space portion in FIG. 7B are exchanged is formed in the pattern region 11 of the base layer 2.

  Next, as shown in FIGS. 8A and 8B, the neutralization film 3, the first domain 51, and the second domain 52 remaining on the base layer 2 are removed, and the base layer 2 is used as a mask. Then, the layer to be processed 1 is etched. Thereby, the line and space pattern of the foundation layer 2 is transferred to the pattern region of the layer 1 to be processed, and a line and space pattern is formed. The non-pattern region 12 of the layer 1 to be processed is not etched because the entire surface is masked by the base layer 2. For example, when the layer 1 to be processed is a quartz glass substrate, the layer 1 to be processed can be removed by dry etching using a fluorine-based gas.

  Etching of the layer 1 may be performed in a state where the neutralization film 3, the first domain 51, and the second domain 52 remain on the base layer 2. Thereby, the number of processes can be reduced.

  As described above, according to the pattern forming method according to the present embodiment, the underlying layer 2 having an affinity for either the first segment or the second segment is exposed. As a result, in the non-pattern region 12, one of the first domain 51 and the second segment is formed as a starting point, and a stacked structure including the layer of the first domain 51 and the layer of the second domain 52 is formed. . Therefore, when removing one of the first domain 51 and the second domain 52, the non-pattern region 12 is masked by the other of the first domain 51 and the second domain 52.

  For this reason, the fingerprint pattern as shown in FIG. 9 is not formed in the non-pattern region 12, and the step of cutting the fingerprint pattern and the protective film forming step for protecting the base layer 2 at the time of cutting are performed. Thus, the number of processes for pattern formation can be reduced. When a fingerprint pattern is formed, a wiring short circuit or the like is caused. Therefore, a process of cutting the fingerprint pattern at the time of cutting or a protective film forming process for protecting the base layer at the time of cutting is required. .

  This pattern forming method can be applied to patterning a quartz glass substrate or the like. Therefore, a template for a photomask or nanoimprint can be manufactured using this pattern forming method. By using this pattern forming method, it is possible to reduce the manufacturing process of a photomask and a template for nanoimprinting and to form a fine pattern.

(Second Embodiment)
A pattern forming method according to the second embodiment will be described with reference to FIG. In the pattern forming method according to the present embodiment, a neutral material is used as the resist material for the first segment and the second segment of the block copolymer.

  First, as shown in FIGS. 10A and 10B, the underlayer 2 is formed on the layer 1 to be processed, and the line-and-space pattern-shaped resist pattern 4 is formed in the pattern region 11 on the underlayer 2. . The resist pattern 4 is formed by spin-coating a resist material on the underlayer 2 and removing a part of the resist material by exposure and development.

  Since the formed resist pattern 4 is neutral with respect to the block copolymer, it functions as the neutralization film 3 in the first embodiment. That is, in this embodiment, the neutralization film 3 is formed of a resist material.

  After forming the resist pattern 4, the block copolymer layer 5 is formed on the underlayer 2 and the resist pattern 4. The subsequent steps are the same as in the first embodiment.

  As described above, according to the pattern forming method according to the present embodiment, the neutralization film 3 can be formed of a resist material. Therefore, steps such as formation and etching of the neutralization film 3 and removal of the resist pattern 4 after etching the neutralization film 3 in the first embodiment are unnecessary, and the number of steps for pattern formation is further reduced. can do.

  In addition, it is also possible to form the resist pattern 4 in the first embodiment with a resist material that is neutral with respect to the block copolymer. In this case, a process such as removal of the resist pattern 4 after the neutralization film 3 is etched is not necessary, so that the number of processes for pattern formation can be reduced.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. Further, for example, a configuration in which some components are deleted from all the components shown in each embodiment is also conceivable. Furthermore, you may combine suitably the component described in different embodiment.

1: Processed layer, 11: Pattern region, 12: Non-pattern region, 13, 14: Micro phase separation pattern, 2: Underlayer, 3: Neutralized film, 4: Resist pattern, 5: Block copolymer layer, 51 : First domain, 52: Second domain

Claims (11)

A first region having a guide pattern and a second region having a higher affinity for one of the first segment and the second segment contained in the self-assembled material than the affinity for the other are formed on the work layer. And
Applying the self-assembling material on the first region and the second region;
Phase-separating the self-assembled material into a first domain having the first segment and a second domain having the second segment;
A pattern forming method including selectively removing either one of the first domain and the second domain. The formation of the second region is as follows:
On the processed layer, an underlayer having a higher affinity for one of the first segment and the second segment than the affinity for the other is formed,
Forming a neutral film neutral to the first segment and the second segment on the underlayer;
The pattern forming method according to claim 1, comprising removing the neutralization film to expose the base layer. The formation of the first region is as follows:
On the processed layer, a base layer having high affinity for either the first segment or the second segment is formed,
Forming a neutral film neutral to the first segment and the second segment on the underlayer;
The pattern forming method according to claim 1, comprising removing the neutralization film in a predetermined pattern to form the guide pattern having the neutralization film and the base layer. After selectively removing either one of the first domain and the second domain,
Etching the neutralization film and the underlayer using the other of the first domain and the second domain as a mask,
The pattern formation method of any one of Claims 1-3 including etching the said to-be-processed layer by using the said base layer as a mask. The pattern forming method according to claim 1, wherein the self-assembling material is a block copolymer. The pattern formation method according to claim 1, wherein the underlayer includes at least one of Si, Mo, Cr, and Ta. The pattern forming method according to claim 1, wherein the layer to be processed is a quartz glass substrate. The pattern forming method according to claim 1, wherein the neutralization film includes a resist material.   The phase separation of the self-organizing material forms a first pattern in which the first domains and the second domains are alternately stacked on the second region. The pattern forming method according to 1.   The photomask manufactured using the pattern formation method of any one of Claims 1-9.   The template for nanoimprint manufactured using the pattern formation method of any one of Claims 1-10.

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